At present, particular types of ink jet printers apply side shooting print heads. Typically, these print heads involve nozzles that shoot in a side direction with respect to a piezoelectric element, and parallel to the silicon wafer. Side shooting piezo print heads allow firing chambers to be placed on both sides of a silicon wafer. This feature allows maximizing the nozzles per linear inch per area of silicon wafer and allows tight packing of print heads in a printer which reduces the carefully controlled paper print zone
Manufacturing these types of print heads involves cutting out a nozzle and an ink chamber in a photolithographic silicon etch process, adhering a flexible membrane above the nozzle and chamber, and adhering a piezoelectric actuator on the membrane positioned above the nozzle and ink chamber. A nozzle orifice surface and the nozzle orifice of the print head are formed by dicing the wafer. The nozzle consists of a converging zone that provides a fluidic path between the chamber and the nozzle orifice. The nozzle orifice consists of a near rectangular opening with a short straight wall region normal to nozzle orifice. A straight region, the chimney, is provided between the converging zone and the orifice, and directs the accelerating fluid flow that will eventually produce the ink drop. The piezoelectric element deforms the membrane which in part provides the acoustic pressure in the ink chamber that ejects the ink from the nozzle orifice in a direction perpendicular with respect to the piezoelectric element/membrane primary deflection direction.
As the nozzle orifice is formed by wafer dicing, process irregularities such as chips are formed along the edges of the nozzle orifice. These irregularities may adversely affect nozzle orifice ink wetting consistency and meniscus shape that is formed near the nozzle orifice. In practice, the drop trajectory may deviate significantly from the intended direction due to interaction of the fluid with the irregularities. Furthermore, the chimney length may vary significantly between different print heads due to the relatively large tolerance imposed by the sawing process.
Currently the nozzle orifice surface is polished to counter irregularities in the sawn surface. Afterwards, the entire die, both outside and inside the nozzles and the chamber, are cleaned. Such polishing and cleaning is a slow and expensive process and generally produces significant yield fall out due to incomplete cleaning and other grit particle induced defects.
Furthermore, during etching undesirable irregularities are formed on nozzle surface opposed to the membrane surface in the chimney region of the nozzle. In use, these irregularities cause asymmetric meniscus shape in the nozzle orifice, that further affect drop trajectory.
A goal of the invention is to alleviate at least one of above drawbacks.